Adaptive Microphone Matching in Directional Hearing Aids
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Solution Overview
Problem
Existing directional hearing aids with multiple microphones face challenges in accurately matching phase characteristics over time due to factors like aging, temperature, and humidity, leading to degradation in directivity and saturation issues, especially with microphones having low-frequency sensitivity.
Innovation Solution
An adaptive real-time microphone matching system that uses a signal processor to measure and model the transfer functions of each microphone channel, minimizing differences by controlling adaptive matching means, allowing for continuous adjustment of microphone poles and RC filter stages to maintain accurate directivity throughout the hearing aid's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If microphones are carefully selected and matched during production to achieve close parameter matching, then manufacturing precision is improved, but device complexity increases and the process becomes time-consuming
Solution Approach 1:
The patent applies preliminary action by performing microphone matching during the production stage through careful selection and pairing of microphones with similar parameters. This upfront matching effort reduces the need for complex adaptive adjustments later, resolving the contradiction by accepting higher initial complexity to achieve better long-term performance stability.
Solution Approach 2:
The patent employs parameter changes by allowing the digital signal processor to dynamically adjust microphone signal parameters (gain, phase) in real-time based on measured transfer functions. This compensates for manufacturing variations without requiring extremely precise initial matching, thus reducing manufacturing precision requirements while maintaining overall system performance.
2Manufacturing precision
If production stage matching is used to achieve close parameter matching, then manufacturing precision is improved, but adaptability deteriorates as microphone characteristics change over time due to aging, temperature, and humidity
Solution Approach 1:
The patent implements feedback by continuously measuring the transfer functions of microphone channels and using this information to adaptively adjust signal processing parameters. This closed-loop system compensates for aging, temperature, and humidity effects, maintaining directivity performance throughout the hearing aid's service life despite initial matching limitations.
Solution Approach 2:
The patent applies dynamics by transitioning from static production-stage matching to dynamic real-time adaptation. The digital signal processor continuously adjusts microphone signal parameters based on current environmental conditions and aging effects, enabling the system to adapt to changing conditions and maintain optimal performance over time.
3Adaptability or versatility
If adaptive real-time microphone matching is implemented, then adaptability is improved to compensate for aging and environmental effects, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting digital signal processing parameters (gain, phase, delay) based on measured transfer functions. This allows compensation for microphone characteristic changes without requiring physical hardware modifications, achieving adaptability through software-based parameter optimization.
Solution Approach 2:
The patent replaces mechanical/physical matching approaches with digital signal processing methods. Instead of relying on precise physical microphone pairing, the system uses digital filtering, gain adjustment, and phase correction to achieve matching, reducing the need for complex mechanical selection processes while enabling flexible real-time adaptation.
4Area of stationary object
If directional microphone systems rely on arrival time differences, then directivity capability is improved, but measurement precision requirements increase to resolve minute phase differences
Solution Approach 1:
The patent applies parameter changes by measuring the complete transfer function (amplitude and phase) across multiple frequencies and using this information to adaptively adjust signal processing parameters. This comprehensive parameter measurement and adjustment approach enables resolution of minute phase differences required for accurate directional sensitivity without requiring excessively precise fixed measurements.
Solution Approach 2:
The patent implements feedback by continuously measuring transfer functions and using this information to adjust signal processing parameters for optimal phase alignment. This closed-loop approach maintains accurate phase difference resolution despite environmental variations and aging, enabling sustained directional sensitivity performance.
Data Source
AI summary
A directional hearing aid (100) comprising at least two microphones (201, 202) has means (200) for matching differences in amplitude and phase between the two microphones (201, 202). The microphone matching means (200) compare differences between measured transfer functions of the microphone signal paths at a number of frequencies during use of the hearing aid (100), compares the differences to differences at similar frequencies in a model of the transfer functions of the microphone signal paths, derives a set of parameters based on the comparison, and adjusts the parameters in order to minimize the difference in level differences between the model and the microphones (201, 202). The model is then used to match the microphones (201, 202) mutually by applying appropriate control parameters (103, 104, 105, 106) to an adaptive matching filter (108) carrying one of the microphone signals.